Ktest: Use dodie for critical falures

Users should get emails when the script dies because of a critical failure.
Critical failures are defined as any errors that could abnormally terminate
the script.

In order to add email support, this patch converts all die() to dodie() except:
 * when '-v' is used as an option to get the version of the script.
 * in Sig-Int handeler because it's not a fatal error to cancel the script.
 * errors happen during parsing config

Link: http://lkml.kernel.org/r/1522094884-22718-4-git-send-email-tianyang.chen@oracle.com

Suggested-by: Dhaval Giani <dhaval.giani@oracle.com>
Signed-off-by: Tim Tianyang Chen <tianyang.chen@oracle.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>